This invention relates to computer generation of documents using layout elements and content elements.
Computer generated human-readable documents, for example, exhibit a wide range of forms including those appearing on paper or other “tangible” media and others that are only temporarily displayed on “intangible” media like the display surfaces of computer monitors.
Tangible documents range from full-color press-printed high-volume books, magazines, and commercial literature to multiple-color laser-printed medium-volume items to one-of-a-kind black-and-white pages printed on personal computer printers. Intangible documents include web pages that are received by telecommunication from a central source, screen displays that are generated by software running on local networks or individual workstations, and digitally-generated video frames.
Human-readable documents include content such as words, numbers, pictures, animations, and video. The content is presented in a way that reflects layout features. Layout features can include the styles in which content is presented (e.g., font, size, shape, color) and the locations and arrangements of elements on pages of a document.
When traditional printing was the predominant method for producing documents, a document tended to have a fixed content and layout. More recently, using computer software, it has become easier to create documents that share common content but different layouts (for example, a web page and a printed sales sheet that have identical texts) or a common layout but different content (different sales sheets that share a common appearance but pertain to different products in a product line).
A document that is created in software typically is stored in a file that captures the layout and content of the document. When the document is to be produced in a tangible or intangible form, a formatter uses the information contained in the document description file to generate the document in a format suitable for the target medium.
Layout and content both have structure. With respect to layout, for example, a box containing an image may contain another image box. Or the layout may require that two text boxes appear side by side on the page. Text has structure that, for example, defines the order of letters or words, or the grouping of sentences in paragraphs. When the formatter generates a document from a document description file, it sometimes must resolve conflicts between structure associated with the content and structure associated with the layout.
Early software tended to mingle content and layout features of a document in the document description file. For example, the text content could be interspersed with escape codes that shifted fonts or redefined the locations of characters.
In more recent software products, the document description files provide a sharper separation between content and layout features. This separation enables a user to make changes to layout without affecting the content (e.g., to change all uses of Times-Bold font in a document to Helvetica-Bold) or to work with the content without changing the layout (e.g., to search the text for a particular string). These recent software products are either content-centric or layout-concentric.
Content-centric software, such as Microsoft Word, emphasizes content in the description files and supplements the content with layout features as needed. The user creates and manipulates text largely independently of the layout. Layout features are added to the text either manually by the user or automatically by the program.
Layout-centric software, such as Adobe's PageMaker7, emphasizes layout features, such as placement of content elements on a page, in the document description files. The user creates and manipulates layout elements. Content is added to the layout-structured document as needed.
The creation of some documents is strongly content-oriented (e.g., a legal brief) or strongly layout oriented (e.g., an advertisement). For other documents, the creation process is a hybrid effort combining both content-centric and layout-centric tasks. In a magazine page that contains an article next to an advertisement, for example, the content may be the focus in creating the article while the layout may be the focus in creating the advertisement.